Process for weakening the hydrophobic behavior of alkene polymers

ABSTRACT

A PROCESS FOR WEAKENING THE HYDROPHOBIC BEHAVIOR OF ALKENE POLYMERS IS DISCLOSED, WHEREIN A POLYMER OR A COPOLYMER OF AN ALKENE IS MIXED WITH (A) 0.05-2% BY WEIGHT OF A MONO- OR DIESTER OF A HEXAVALENT, PARTLY DEHYDRATED ALCOHOL AND AN ALIPHATIC CARBOXYLIC ACID HAVING 12-22 CARBON ATOMS, AND (B) 0.01-0.5% BY WEIGHT OF AN AMIDE OF AN ALIPHATIC CARBOXYLIC ACID HAVING 12-22 CARBON ATOMS.

United States Patent U.S. Cl. 26085.7 4 Claims ABSTRACT OF THE DISCLOSURE A process for weakening the hydrophobic behavior of alkene polymers is disclosed, wherein a polymer or a copolymer of an alkene is mixed with (a) 0.05-2% by weight of a monoor diester of a hexavalent, partly dehydrated alcohol and an aliphatic carboxylic acid having 12-22 carbon atoms, and (b) 0.01-0.5% by weight of an amide of an aliphatic carboxylic acid having 12-22 carbon atoms.

BACKGROUND OF THE INVENTION Polymers and copolymers of alkenes have a pronounced hydrophobic character. This may be a drawback in the application of objects made of polyalkenes, particluarly in the application of transparent films as packaging material under conditions where water vapour is liable to condense on their surface. Such films are an excellent packaging material for dry goods, but they are less suitable for packaging moist or moisture-containing products, such as fresh meat products, vegetables, flowers and fruit, because the evolving water vapour is apt to condense as rninute droplets on the inner surface of the film, which, in consequence, gets misted over, with the result that the visibility of the packed articles is decreased.

It has already been proposed to reduce this misting effect on polyalkene films by mixing the polyalkenes with an ester, an ether, an amine or an amide, containing at least one oxyethylene group and one alkyl or acyl group with 12-22 carbon atoms or with a mono-ester or diester of sorbitan and a fatty acid with 12-22 carbon atoms (see Belgian patent specifications 615,683 and 615,684). However, the improvement that can thus be achieved is not suificient in many cases.

DESCRIPTION OF THE INVENTION The present invention aims at an improved process for weakening the hydrophobic behavior of polymers and copolymers of alkenes.

Another object of the invention is to provide a transparent packaging film made of such polymers.

The process according to the invention for weakening the hydrophobic character of alkene polymers is characterized in that a polymer, or copolymer, of an alkene is mixed with (a) a 0.05-2% by weight of monester, or a diester, of a hexavalent, partly dehydrated alcohol, and an aliphatic carboxylic acid with 12-22 carbon atoms, and (b) 0.01-0.5% by weight of an amide of an aliphatic carboxylic acid with 12-22 carbon atoms.

The abovementioned esters include esters of partly dehydrated hexitols, such as mannitan and sorbitan with saturated and unsaturated fatty acids, such as lauric acid, steric acid, oleic acid and erucic acid. Preference is given to the mono-esters, particularly to those of mannitan and sorbitan and a saturated fatty acid. Suitable carboxylic acids are both the amids of saturated and unsaturated fatty acids with 12-22 carbon atoms, such as lauric-, palmitic-, stean'c-, oleicand erucic acid-amide. The amide of oleic acid is particularly suitable. Very good results are obtained with a mono-ester of a dehydrated hexitol 3,557,248 Patented Jan. 19, 1971 ice and a saturated fatty acid with 12-18 carbon atoms in combination with an amide of an unsaturated fatty acid with 18-22 carbon atoms. The combination of sorbitan monolaur ate and oleic acid amide weakens the hydrophobic behavior of the alkene polymers to a very high degree, and is therefore particluarly recommendable.

The esters are used in amounts of 0.05-2% by weight preferably 0.2-0.5 by weight, calculated to the amount of polymer. It is preferred to take the amounts of carboxylic acid amide smaller than the amount of ester, more specifically between 0.01 and 0.5% by weight, and preferably between 0.03 and 0.1% by weight, calculated to the amount of polymer.

The process according to the invention can be used with homopolymers and copolymers of alkenes, for example polyethylene, polypropylene, poly-(4-methylpentene-1), copolymers of ethylene and propylene with one another or with some other alkene, such as butylene-l, pentylene-l, hexylene-l and octylene-l and copolymers of alkenes with other unsaturated compounds e.g. copolymers of ethylene with unstaurated esters such as vinylacetate and methylacrylate.

Mixing the esters and the amides with the alkene polymers does not give any difficulties and can be done in a known manner, e.g. in mixing or kneading installations. The ester and the amides can be used in combination with other additives normally used with polyalkenes, e.g. dyes, fillers, antioxydants, antistatics, anti-blocking agents, such as silica and silicates, etc.

The mixtures prepared according to the invention, can by means of the procedures known in the art, be manufactured into transparent objects, eg, injection-molded articles, bottles and stretched or unstretched flat films, or blown films, having a less hydrophobic character than objects made of polyalkenes that do not contain the additives used according to the invention. Said mixtures can also be applied as film or coating on other materials, for instance on paper. The mixtures are, of course, also suited for production of non-transparent objects with a reduced hydrophobic behavior.

EXAMPLE and no water droplets were present on the film surface.

By way of comparison, the test was repeated with films made of the same polyethylene which, however, did not contain any of the two additives, or only 0.3% by weight of sorbitanmonolaurate or only 0.05% by weight of oleic acid amide. These films lost their transparency in 2, 10 and 5 days respectively, through formation of minute water droplets on the surface.

As sorbitanmonolaurate is a known antistatic, and it is assumed that the antistatic properties of a compound are related to its antihydrophobic properties, a similar test was made with a number of films made of the abovementioned polyethylene to which several other antistatics, with and without oleic acid amide, had been added. The results of this test are given in the table in col. 3. The table also gives the surface resistance, measured in conformity with ASTM D257-61, and the frictional resistance determined in conformity with ASTM D1894-63.

The table shows that oleic acid amide in combination with sorbitanmonolurate gives a synergistic effect-but not so with other antistaticswithout lowering the antistatic eifect of the sorbitanmonolaurate. Curiously enough,

3 however, it no longer acts as a lubricant; the friction coefiicient is even higher than that of the blank.

4. Process according to claim 3 wherein the monoester of a dehydrated hexitol and a saturated fatty acid with Oleic Days during acid which the amide, Surface film retains Percent Percent resistance, Friction its trans Antistatic by wt. by wt. ohm coeii. parency Sorbitanmonolaurate 0. 3 7X 10 O. 7 10 0.05 10 0.5 5

Do 0.3 0.05 7X10 2 180 C1 Ha5(OCH2CI-Iz)aCOOH. 0.3 5x10 0.7 5 Do 0.3 0.05 1X10 2 5 Monamide 150 LWA 0. 3 3X 2 5 D 0. 3 0.05 3X10 2 5 0.3 3X10 0.6 10

0 0.3 0.0 7X10 2 10 Atlas GB 4061 0.3 1. 6X10 2 10 Do 0.3 0.05 2 10 2 10 What is claimed is:

1. Process for weakening the hydrophobic behavior of a polymer selected from the class consisting of homopolymers of an olefine, copolymers of mixtures of olefins and copolymers of alkenes with unsaturated esters wherein said polymer is mixed with:

(a) 0.05-2% by Weight, based on the amount of polymer of a mono-ester or diester of a hexavalent, partially dehydrated alcohol and an aliphatic carboxylic acid with 12 to 22 carbon atoms, and

(b) 0.01-0.5% by weight, based on the amount of poylmer of an amide of an aliphatic carboxylic acid with 12 to 22 carbon atoms, said acid amide selected from the class consisting of lauric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide and erucic acid amide.

2. Process according to claim 1, characterized in that the polymer is mixed with 02-05% by weight, based on the amount of polymer, of the ester and 0.03-0.1% by weight, based on the amount of polymer, of the amide.

3. Process according to claim 1, characterized in that a mono-ester of a dehydrated hexitol and a saturated fatty acid with 12-18 carbon atoms is used in combination with an amide of an unsaturated fatty acid with 18-22 carbon atoms.

12-18 carbon atoms is sorbitanmonolaurate and the amide of an unsaturated fatty acid with 18-22 carbon atoms is oleic acid amde.

HOSEA E. TAY-LOR, Primary Examiner R. W. GRIFFIN, Assistant Examiner U.S. C1.X.R. 

